The following terms when used in relation to computer code or computer functions shall have the meanings provided.
(1) "Application" refers to a single set of functions that support a specific requirement. For example, in computer integrated manufacturing, production equipment maintenance (PEM) can be supported by a PEM application.
(2) "System" refers to a collection of applications that support an overall business. For example, in computer integrated manufacturing, the overall manufacturing business can be supported by a manufacturing execution system (MES).
(3) "Architecture" refers to the foundation and guidelines that all systems within a business follow. For example, for a host-based architecture, host configuration, network design, and data access are all part of the architecture.
(4) "Platform" refers to sections of the foundation for the overall system. For example, Windows NT.RTM. is a platform.
Migration of legacy applications is imperative in the modern manufacturing environment. For example, semiconductor manufacturers need to find ways to extend the life of their existing fabricators despite limitations on existing computer integrated manufacturing (CIM) systems; specifically, such systems cannot support state-of-the-art process control technology. Existing systems have been in place for many years and have evolved into their present condition. With the creation of object technology, frameworks, and other system developments, CIM products are now capable of handling the latest process technology through the use of "plug-and-play" modules. Current CIM products also have the ability to implement business practice changes rapidly and without massive programming efforts.
Unfortunately, the migration of legacy software applications (e.g., pre-existing applications performed by a predecessor software system) to new architectures is difficult and expensive. Each legacy application is typically intertwined with other applications to such an extent that migrating any one section of a system would have a negative impact on many other sections of the system. The only available alternative has been migration of the entire legacy platform. This alternative is prohibitive, however, given the substantial resources requirements, both in costs and labor, and resulting extended system down time.
The deficiencies of the conventional attempts to migrate legacy software applications to new architectures show that a need still exists for an improved migration methodology. To overcome the shortcomings of the conventional attempts, a new methodology is provided. An object of the present invention is to provide an economic method for migrating legacy applications into a new product architecture which minimizes system down time. It is a further object of this invention to provide a method for migrating legacy applications in which current data are maintained on the legacy applications for a sufficient period of time to provide a back out option until the application can be verified on the new product architecture.